Submersible motor-pump construction



Jan. 17, 1967 JOHNSON ET AL 3,298,318

SUBMERSIBLE MOTOR-PUMP CONSTRUCTION Filed Jan. 21, 1965 INVENTORS IRVINGA. JOHNSON STEPHEN STASENKO 3,298,318 Patented Jan. 17, 1967 7 3,298,318SUBMERSIBLE MOTOR-PUMP CONSTRUCTION Irving A. Johnson and StephenStasenko, Erie, Pa., as-

siglors to A. O. Smith Corporation, Milwaukee, Wis., a corporation ofNew York Filed Jan. 21, 1965., Ser. No. 426,722 3 Claims. (Cl. 103108)This invention relates to a submersible motor-pump unit, and moreparticularly to an improved :pump construction for a submersiblemotor-pump unit.

Submersible motor-pump units are employed for pumping gas or petroleumproducts from underground tanks to dispensing units located above theground. In the conventional submersible motor-pump unit, the pump islocated beneath the motor and the pump impellers are secured to thelower end of the motor shaft. A pump housing surrounds the impellers,and a series of diffuser sections are located within the housing betweenthe impellers and serve to guide the liquid from one stage impeller tothe next.

The present invention is directed to an improved pump construction forsubmersible motor-pump units which simplifies the assembly anddisassembly of the pump and improves the flow characteristics of theliquid being pumped. More specifically, the pump construction includes aseries of impellers which are keyed to the lower end of the motor shaft.The pump housing is threaded onto an adapter connected to the lower endof the motor and surrounds the impellers. According to the invention,the pump housing is provided with a series of diffuser sections whichare cast integrally with the housing and extend between the impellers.Each diffuser section is provided with a series of guide vanes and abafile plate is secured to the vanes to provide a closed diffusersection which results in less turbulence in the liquid flow and a moreefiicient output.

An end cap is threaded onto the lower end of the pump housing and isprovided with an inlet flange which bears against the series ofimpellers and maintains the impellers in position on the motor shaft.

By unthreading the end cap, the lower impeller can be readily removedfor service or replacement and by unthreading the pump housing the upperimpeller can be replaced. This results in a unit that can be morereadily assembled and disassembled than the conventional motorpump unit,for it requires only two elements to be unthreaded to completelydis-assemble the entire pump construction.

As an additional feature, the impellers are designed to provide improvedflow characteristics for the liquid. Each impeller is provided with aseries of generally curved blades which extend between upper and lowerplates. The upper or top surface of the impeller converges toward thelower surface in a radial direction so that the crosssectional areabetween the impeller blades remains substantially constant throughoutthe radial extent of the impeller. This serves to reduce cavitation andprevent disruption of fluid flow characteristics.

Other objects and advantages will appear in the course of the followingdescription.

The drawings illustrate the best mode presently contemplated of carryingout the invention.

In the drawings:

FIGURE 1 is a longitudinal section with parts broken away of themotor-pump unit of the invention,

FIG. 2 is a transverse section, with parts broken away, taken along line2-2 of FIG. 1, and

FIG. 3 is a transverse section, with parts broken away, taken along line33 of FIG. 1.

The drawings illustrate a submersible motor-pump assembly which can beused for pumping petroleum products from underground tanks to dispensingunits located above ground. The motor-pump assembly includes a motorunit 1 which is located within an outer generally cylindrical,thin-walled shell 2. A discharge fitting 3 is connected by bolts 4 tothe upper bearing housing 5 of the motor unit 1 and is provided with aseries of liquid outlets 6 which communicate with passages 7 formed inthe housing 5 of the motor unit. The liquid is conducted upwardlythrough the annular clearance 8 between the motor unit 1 and shell 2 andthen flows through passages 7 and outlets 6 to the discharge conduit 9threaded in the central opening in fitting 3. 7

Electrical energy is supplied to the motor unit 1 throug electricalconduit 10 which is provided with a plug 11 engaged with socket 12located in the upper bearing housing 5. The motor unit 1 and dischargefitting 3 are of convention-a1 construction and in themselves form nopart of the present invention.

7 An adapter ring 13 is secured to the lower bearing housing 14- of themotor unit 1 by a series of bolts 15 and the adapter isprovided with acentral opening 16 through which the motor shaft 17 projects. Theadapt-er ring 13 is provided with liquid passages 18 which communicatewith the annular space 8 between the motor unit 1 and the shell 2.

The lower end 19 of motor shaft 17 is splined and carries a pair ofimpellers 20 and 21. Each impeller is provided with a central hub 22having a splined interior surface which is engaged with the splinedshaft end 19. The splined connection prevents relative rotation betweenthe mot-or shaft 17 and the impellers, yet permits the impellers to bemoved axially along the shaft.

' Each impeller 20 and 21 is provided with a generally sloping or convexupper surface 23 and a generally fiat lower surface 24. The surface 20is provided with a downwardly extending flange 25 which defines an inletopening 26 through which the liquid is introduced into the respectiveimpeller.

As best shown in FIG. 3, each impeller 20 and 21 is provided with aseries of generally curved blades 27. The blades extend from a locationadjacent the periphery of the impeller to a position adjacent the hub22. As the upper surface 23 slopes or tapers toward the lower surface24, the height or distance between the surfaces 23 and 24 progressivelydecreases in a direction radially outward. This decrease in heightbalances the increase in dimension between the adjacent blades 27 in adirection radially outward so that the cross-sectional area defined bysurfaces 23 and 24 and adjacent blades 27 remain substantially constantin a .direction radially outward of the impeller. By maintaining thecross-sectional area sub stantially constant, the cavitation is reducedand more uniform flow characteristics are provided which increases 7 theefliciency of the pumping unit.

The impellers 20 an'd'21 are housed within a generally cylindricalhousing 28 which is threadedly engaged with the lower end of the adapterring 13. 'The housing 28 is sealed to the ring 13 by use of an O-ringseal 29 which is located within a circumferential recess formed in theouter surface of the ring 13.

As best shown in FIG. 1, the upper edge of housing 28 is provided with ashoulder 30 and the lower end of the motor shell 2 bears against theshoulder so that the peripheral surface of housing 28 is flush with theouter surface of motor shell 2. The motor shell 2 is sealed to theadapter ring 13 by an annular seal 31 which is also located within arecess formed in the adapter ring 13.

According to the invention, the pump housing 28 is provided with aninternal diffuser ring 32 which is cast integrally with the housing 28.The diffuser ring 32 extends radially inward between the impellers 20and 21 and is provided with a series of generally curved vanes 33 whichserve to guide and diffuser the liquid from the lower impeller 21) tothe upper or second stage impeller 21.

In addition to the diffuser ring 32, an annular baffle disc 34 issecured to the lower edges of the vanes 33 by screws 35 and the baffledisc 34 provides a closed diffuser section which reduces the turbulenceand provides a more uniform flow of liquid to the second stage impeller21.

The inner annular edge of bafiie disc 34 is provided with a flange 36which is disposed around the hub 22 of impeller 20.

The lower end of the pump is enclosed by an end cap 37 which is threadedto the lower end of the pump housing 28. The cap 37 is provided with aninlet opening 38 which communicates with a central passage 39 defined bythe annular flange 40. Flange 40 has a slightly greater internaldiameter than the external diameter of the flange 25 bordering theopening 26 of the impeller 20 so that the flange 25 will be locatedradially inward of the flange 40.

In operation, the liquid to be pumped is drawn in through the opening 38in end cap 37 and flows through passage 39 to opening 26 of the firststage impeller 20. The liquid is thrown radially outward by the bladesof the impeller and passes inwardly between the diffuser vanes 33 to theinlet 26 of the second stage impeller 21. The

impeller 21 throws the liquid outwardly and it passes' through thepassages 18 in the adapter ring 13 into the annular clearance 8 betweenthe shell 2 and the motor unit 1. The liquid then flows through thepassages 7 and outlets 6 to the discharge conduit 9 leading aboveground.

The present invention provides a pump construction which can beassembled and dis-assembled with a minimum amount of labor. By merelyunthreading the end cap 37 from the housing 28, access can be had to thelower impeller 21 and by unthreading the housing 28 from the ring 13.The upper impeller 21 can be removed from the motor shaft.

The construction reduces the number of parts in that the pump housing isformed integrally with the diffuser ring. In a conventional unit, aseries of diffuser sections are stacked within an outer pump housing,while in the present construction the diffuser ring is an integral partof the pump housing so that only a single element is required.

The bafHe 34 which is secured to the vanes 33 of the diffuser ringserves to produce a less turbulent flow of liquid and a more eflicientoutput. In addition, the impellers 20 and 21 are shaped so that thecross-sectional area between the impeller blades is substantiallyconstant throughout the radial extent of the impeller. This again servesto prevent cavitation and provides a more uniform flow of liquid throughthe pump assembly.

While the above description is directed to the use of the pumpconstruction in a submersible motor-pump unit, it is contemplated thatthe pump construction can be employed with any type of conventionalmulti-stage pumping unit.

Various modes of carrying out the invention are con- 4 templated asbeing within the scope of the following claims particularly pointing outand distinctly claiming the subject matter which is regarded as theinvention.

We claim:

1. In a pump construction, a rotatable shaft, a series of impellersmounted on the shaft for rotation therewith, said impellers being freelymovable on said shaft in an axial direction, a generally cylindricalhousing disposed radially outward of the impellers and having a diffusersection extending radially inward between said impellers, and an end capthreadedly engaged with the outer end of said housing and having anannular portion spaced radially between the axis of said shaft and thehousing and portion disposed to bear against an axially facing surfaceon the outermost impeller in said series to retain said impellers onsaid shaft, said cap having an inlet opening providing communicationwith the outermost impeller and liquid being moved by said outermostimpeller through the diffuser section to the next impeller in theseries.

2. In a pump construction, rotatable shaft, a series of impellersmounted on said shaft for rotation therewith, said impellers beingfreely disposed on said shaft with respect to axial movement, agenerally cylindrical housing disposed radially outward of the impellersand having a diffuser section extending radially inward between saidimpellers, and an end cap threadedly engaged with the outer end of thehousing and having an annular disposed to bear against an axially facingsurface on the outermost impeller in said series of retain saidimpellers on said shaft,

the outer end of said shaft being free of radially extending abutmentswhereby the outermost impeller can be slipped from the shaft afterremoval of said end cap.

3. In a pump construction, a rotatable shaft, a series of impellers witheach impeller having a central hub mounted on the shaft for rotationtherewith, said impellers being freely disposed on said shaft formovement in an axial direction, a generally cylindrical housing disposedradially outward of the impellers and having a diffuser sectionextending radially inward between said impellers, and an end capthreadedlyl engaged with the outer end of said housing and having anaxial inlet opening, said end cap having an annular bearing portionlocated between said inlet opening and the housing, the outermostimpeller in said series having an axially facing-surface disposed to'bear against said annular bearing portion to retain said impellers onsaid shaft, and the entire outer end surface of the hub of saidoutermost impeller being exposed, whereby the outermost impeller can beslipped from the shaft after removal of said end cap.

References Cited by the Examiner UNITED STATES PATENTS 1,908,627 5/1933Moran et a1.

2,165,808 7/1939 Murphy 103-415 2,689,529 9/1954 Wightman 103108 X3,031,973 5/1962 Kramer 103108 X 3,158,295 11/1964 McConaghy 103-108 XRO ERT M, WAL E Primary x m e Patent No. 3, 298, 318 January 17, 1967Irving A. Johnson et al.

in the above numbered petthat error appears ent should read as It ishereby certified that the said Letters Pat ent requiring correction andcorrected below.

line 27, beiore Column 4, line 13, strike out "portion"; "disposed"insert portion line 29, for "of" read for "threadedlyl" read threadedlyto line 40,

Signed and sealed this 7th day of November 1967.

(SEAL) Attest:

EDWARD M. FLETCHER,JR. EDWARD J BRENNER Commissioner of PatentsAttesting Officer

1. IN A PUMP CONSTRUCTION, A ROTATABLE SHAFT, A SERIES OF IMPELLERSMOUNTED ON THE SHAFT FOR ROTATION THEREWITH, SAID IMPELLERS BEING FREELYMOVABLE ON SAID SHAFT IN AN AXIAL DIRECTION, A GENERALLY CYLINDRICALHOUSING DISPOSED RADIALLY OUTWARD OF THE IMPELLERS AND HAVING A DIFFUSERSECTION EXTENDING RADIALLY INWARD BETWEEN SAID IMPELLERS, AND AN END CAPTHREADEDLY ENGAGED WITH THE OUTER END OF SAID HOUSING AND HAVING ANANNULAR PORTION SPACED RADIALLY BETWEEN THE AXIS OF SAID SHAFT AND THEHOUSING AND PORTION DISPOSED TO BEAR AGAINST AN AXIALLY FACING SURFACEON THE OUTERMOST IMPELLER IN SAID SERIES TO RETAIN SAID IMPELLERS ONSAID SHAFT, SAID CAP HAVING AN INLET OPENING PROVIDING COMMUNICATIONWITH THE OUTERMOST IMPELLER AND LIQUID BEING MOVED BY SAID OUTERMOSTIMPELLER THROUGH THE DIFFUSER SECTION TO THE NEXT IMPELLER IN THESERIES.